A hot-melt adhesive is a solvent-free adhesive and has a characteristic that instant bonding and high-speed bonding can be achieved since adhesiveness is exhibited after the adhesive is melted by heating and coated onto an adherend, followed by cooling to solidify the adhesive, and therefore has been used in a wide range of fields. Not only adherends to be bonded with such a hot-melt adhesive but also the conditions of use thereof are various. At present, various hot-melt adhesives for use in various applications have been developed and supplied to the market. Also for the conditions of use, various operating temperatures ranging from low temperatures to high temperatures are considered, and recently, hot-melt adhesives excellent in heat resistance have become desired.
For example, PTL 1 discloses a hot-melt adhesive for use in woodworking or cabinetmaking, which contains a mixture prepared by mixing two copolymers produced using a different metallocene catalyst and having a different melt flow index, in a specific blending ratio, at least one polymer, at least one resin and/or at least one wax, and an additive.
PTL 2 discloses a hot-melt adhesive containing 1 to 30 parts by mass of a propylenic polymer satisfying a specific stereoregularity relative to 100 parts by mass of an ethylenic polymer therein.
PTL 3 discloses a hot-melt adhesive containing a propylene homopolymer obtained through polymerization of propylene using a metallocene catalyst and having a melting point of 100° C. or lower, and an ethylenic copolymer.